Hysteresis motors are self-starting synchronous machines which use the hysteretic properties of their rotors, the driving force being provided by the rotating stator fields which magnetize the magnetic components of the rotors. The torque developed by the motor in each instance is proportional to the area of the hysteresis loop of the rotor magnetic component but the greater the area of hysteresis loop, the greater the coercive force and the greater the exciting current required for operation. Consequently, control of the area of the loop to meet motor design requirements is necessary. In accordance with prior art practice, that necessity is met through composition selection and burdensome special processing measures.
Another persistent problem associated with the fabrication of hysteresis motors is their material and production costs, the essential alloys (such as the commercial alloy known as P-6, the composition of which on the weight basis is 44.5 percent iron, 45.0 percent cobalt, 6.0 percent nickel and 4.5 percent vanadium) being relatively expensive and requiring repeated cold working and high temperature annealing operations.